1. Field of the Invention
The present invention relates to digital broadcasting and more particularly to a data broadcasting system that can handle broadcasting data in a Hi-Vision format and to a data broadcasting contents transmitting system, a receiver, and a format converting method used in same.
The present application claims priority of Japanese Patent Application No. 2004-089004 filed on Mar. 25, 2004, which is hereby incorporated by reference.
2. Description of the Related Art
In recent years, attention is being focused on data broadcasting service provided by ground wave digital broadcasting. The data broadcasting service is service in which videos and/or voices to be broadcast on television are transmitted by ground waves and, at the same time, data broadcasting programs made up of images (including pictures), characters, or a like are transmitted. The data broadcasting programs include news, traffic information, weather information, stock-price information, or a like. In order to receive such digital broadcasts, a specially-designed receiver called an IRD (Integrated Receiver/Decoder) is used.
Ordinarily, the IRD can be connected to two types of monitors including an HDTV (High Definition Television) monitor and an SDTV (Standard Definition Television) monitor. There are two types of digital broadcasting formats, one being an HDTV format and another being an SDTV format. In the case of operations of the IRD, if a broadcasting format of a received video signal being not applicable to a monitor being connected then, a format of the received video signal is converted. For example, in a state in which the SDTV monitor is connected to the IRD, when the IRD receives a video signal in the HDTV format, a conversion called a “down-conversion” is performed in which the received video signal in the HDTV format is converted into a video signal having an optimum resolution enabling the SDTV monitor to display the video signal. On the contrary, in a state in which the HDTV monitor is connected to the IRD, when the IRD receives a video signal in the SDTV format, a conversion called an “up-conversion” is performed in which the received video signal in the SDTV format is converted into the video signal having an optimum resolution enabling the HDTV monitor to display the video signal (see Japanese Patent Application Laid-open No. Hei 2004-40696.
FIG. 20 is a block diagram schematically showing configurations of a conventional data broadcasting system. The data broadcasting system employs the HDTV broadcasting format and has a transmitting system 100 to transmit data broadcasting contents and a receiver (IRD) 200 to receive data broadcasting contents transmitted from the transmitting system 100.
The transmitting system 100 includes a multiplexing section 103 to receive preset HDTV video contents 101 and HDTV data contents 102 and to multiplex these HDTV video contents 101 and HDTV data contents 102 and a modulating section 104 to modulate the multiplexed contents, and an RF (Radio Frequency) signal transmitting section 105 to transmit the modulated contents (data broadcasting contents). The HDTV video contents 101 are made up of a video signal for the HDTV and voice data. The HDTV data contents 102 are contents of data broadcast to be transmitted in synchronization with the HDTV video contents which contains data such as images (pictures) and characters.
The IRD 200 includes an RF signal receiving section 201 to receive data broadcasting contents transmitted from the transmitting system 100, a demodulating section 202 to demodulate the received data broadcasting contents, a multiplexing separation section 203 to separate the demodulated contents into HDTV video contents 204 and HDTV data contents 205, a video/data synthesizing section 206 to synthesize the HDTV video contents 204 and HDTV data contents 205 to obtain HDTV display data, an HDTV outputting terminal 207 to output HDTV display data to an outside, an SDTV outputting terminal 209 to output the SDTV display data to an outside, and a down-scaling section 208 to down-scale the HDTV display data (that is, to down-convert) to a resolution applicable to the SDTV monitor to obtain SDTV display data.
In the above data broadcasting system, if the HDTV monitor is connected to the HDTV outputting terminal 207 of the IRD 200, the HDTV display data is displayed, as it is, on the HDTV monitor. On the other hand, when the SDTV monitor is connected to the SDTV outputting terminal 209 of the IRD 200, the SDTV display data that can be obtained by down-scaling the HDTV display data is displayed in the SDTV monitor.
However, the conventional data broadcasting system is operated in a manner in which SDTV display data is obtained by down-scaling HDTV display data and, therefore, has following problems.
In the process of down-scaling HDTV display data, in order to obtain SDTV display data, information about the HDTV display data is partially trimmed down. As a result, information about data (video contents and data contents) to be displayed on the SDTV monitor is partially lost. The partial losing of information exerts little influence on displaying of video contents due to characteristics of eyes of a human, but exerts influence on displaying of data contents; that is, a problem of degradation in quality such as deformation of characters and/or pictures occurs.
FIG. 21 is a diagram for schematically illustrating degradation in image quality of data contents caused by the down-scaled process described above. In the example shown in FIG. 21, SDTV display data is obtained by partially deleting, on every unit scanning line, HDTV display data in which a character “A” is largely displayed in a center of a display screen. As a result, if SDTV display data is displayed on the SDTV monitor, a deformed character “A” is displayed. Such deformation of a character can be easily recognized in particular.
Moreover, in recent years, an object synchronizing data broadcasting system by which an object (person or thing) contained in an image to be broadcast and its related data are transmitted with the object being associated with data is developed and is partially put in practical use. In the object synchronizing data broadcasting system, when an object on a display screen, for example, a work of art is input by a pointer or a like in a specified manner, detailed information about the work of art (name and history of the art object, place being presently exhibited, or a like) is displayed on the display screen. If such object synchronizing data broadcasting system is applied to a digital broadcast in the HDTV format, following problems caused by a down-scaled process occur.
That is, in the transmitting system 100, HDTV display data and object synchronizing data (data contents) obtained by associating information about a position of an object contained in the HDTV display data and its detailed information are transmitted all together. The information about a position of an object is information about the position where the object is to be displayed on the display screen and the detailed information about the object is displayed in a manner to be linked to the position of the object to be displayed. However, when the down-scaled HDTV display data is displayed on the SDTV monitor, since information about video contents is missing, a position of the object on the display screen is not properly linked to its detailed information. As a result, a problem occurs that, even if the object is input in a specified manner, the detailed information about the object is not correctly displayed on the display screen of the SDTV monitor.
FIG. 22 is a diagram schematically showing a relation among object synchronizing data, HDTV display data, and SDTV display data. In the example, HDTV display data 301 is produced from broadcast contents 300 obtained by multiplexing HDTV video contents and HDTV data contents and SDTV display data 302 is produced by down-scaling the HDTV display data 301. Moreover, object synchronizing position data 303 is produced from the HDTV video contents.
When the HDTV display data 301 is displayed on the HDTV monitor, a position of the object and the object synchronizing data 303 are linked to each other and, therefore, if an object is input in a specified manner, detailed information about the object is displayed correctly. On the other hand, if the SDTV display data 302 obtained by down-scaling the HDTV display data 301 is displayed on the SDTV monitor, due to a loss of information, the position of the object on a display screen and the object synchronizing position data are not linked correctly. As a result, when an object is input in a specified manner, detailed information about the object is not displayed correctly.
Thus, the above conventional method in which SDTV display data is obtained by down-scaling HDTV display data has a problem. That is, if the conventional method is used, due to a loss of information, it is impossible to achieve displaying intended and desired by a provider (broadcaster) of data broadcasting contents.